Page 107 - Journal of Special Operations Medicine - Fall 2015

of LDK. The resulting 530 patients had a median age of
Anesthesia – translated means “without feeling.” 40 years. The indications for the LDK administration
Anesthesia enables the performance of medical were diverse and many patients had underlying medi-
procedures that would cause severe or intolerable cal conditions. These conditions included hypertension
pain if the patient were not medicated. (26%), psychiatric illness (12%), chronic obstructive
pulmonary disease (COPD) (11%), and coronary ar-
Analgesia – translated means “without pain.” tery disease (4%). Intravenous administration was used
It is an aspect of general anesthesia, the reduction 93% of the time. Notably, there was no change in the
of pain. heart rate or systolic blood pressure within 1 hour of
ketamine administration. Ketamine was given for a
system to the brain. This interference is one way in broad range of complaints, including abdominal pain
which the brain is still able to maintain generally normal (33%), back pain (12%), and chest pain (5%).
brainstem control of cardiovascular output and respira-
tory drive. In layman’s terms, ketamine “cuts the brain The study found a 6% adverse event rate for the LDK
off” from external stimuli. At high doses, ketamine al- administration. Table 1 lists the adverse events and
lows for the induction of a completely dissociative state percentages. About 1.5% developed transient hypoxia
while still maintaining cardiorespiratory function. Ket- (7 of 530 patients). All except one of these patients re-
amine achieves this with a high degree of safety. Once sponded to the use of a nasal cannula. The one patient
all NDMA receptors are bound, there is no potential who did not respond required additional bimodal venti-
for further drug action—only an increased duration of lation ( BiPAP). This patient was hypoxic at triage. Four
effects. of these seven patients had also received opioids. One
percent (five patients) had emesis, and all cleared their
With these mechanisms in mind, there remains a thera- airways without assistance.
peutic window for “low dose” in which only some of the Table 1 Study adverse events of Low Dose Ketamine
NDMA receptors are bound. This limits, but does not
completely block, all external stimuli, providing an an- 1.5% transient hypoxia
algesic effect without complete mind–body dissociation. 1% emesis
3.5% dysphoric reactions
Study Methodology
This was a retrospective study looking at LDK in a single Eighteen patients (3.5%) experienced dysphoric sys-
emergency department (ED), a large US Level 3 trauma tems. These included visual hallucinations, agitation,
center. The patients were consecutive, and the data were and unusual behavior. The specific complaints are listed
collected from the electronic medical records during a in a table within the article by Ahern et al and include
period of 2 years from January 2012 to December 2013. the patients’ specific comments: “I feel like I’m flying,”
Any patient who received ketamine as an agent for an- “My pain is gone, but I feel crazy,” or “I feel like a zom-
algesia was eligible. This included those who received bie.” Most patients improved with reassurance. Three
the drug alone or in combination with other analgesic of the 18 received lorazepam. One patient experienced
drugs. Allergy to ketamine was the only absolute con- a moderate to severe reaction; he experienced scream-
traindication. Relative contraindications included age ing and was pulling at the gurney side rails. He received
younger than 18 years, uncontrolled seizure activity, lorazepam and his symptoms resolved. Notably, none of
severe signs of elevated intracranial pressure, renal or the adverse events changed disposition or caused per-
liver failure, and pregnancy or breastfeeding. Selection manent harm.
criteria included LDK use, less than 20mg IV or 25mg
IM. The data were extracted by two trained research- Study Conclusion
ers. Detailed review of the chart was done looking for The authors conclude that LDK alone or in combina-
adverse events within 1 hour of LDK. tion with other pain medications in a diverse ED pa-
tient population appears to be safe and feasible for the
Adverse events were defined as cardiac arrest, apnea (re- treatment of many types of pain. Minor psychomimetic
spiratory rate less than 10) or need for jaw thrust or side effects were observed but easily addressed by ED
bag-valve mask, hypoxia, hypertensive emergency, la- personnel. Emesis and hypoxia were observed but ap-
ryngospasm, emesis, psychomimetic reaction (agitation, pear to be equally or less common that reported with
hallucinations, or unusual behavior), or any other event opioids.
as recorded by medical personnel.
Discussion
Study Results
The researchers found 683 cases of ketamine use in their This is a landmark study supporting the use of LDK
ED during that study period. Of these 153 cases were in a wide range of patients. The study did not address
excluded because the dose exceeded their defined limits the efficacy of ketamine for pain relief; this has been

Ketamine in the Emergency Department 95